It could be. What always puzzled me is.

Apply the keystone.

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What kind of keystone could be “applied”?

Another MAJOR keystone is this one. For the Federal government, these are the people that actually run the government.

https://www.opm.gov/faq/ses/what-does-the-ses-insignia-symbolize-2.ashx

Senior Executive Service FAQ

Question

What does the SES insignia symbolize?

Answer

The SES insignia or emblem represents a keystone -- the center stone that holds all the stones of an arch in place. This represents the critical role of the SES as a central coordinating point between Government's political leadership which sets the political agenda and the line workers who implement it. Members of the SES translate that political agenda into reality. The upright lines in the center of the keystone represent a column in which individual SES members are united into a single leadership corps. There is no particular symbolism to the number of lines, which has varied over the years with different iterations of the logo. The SES insignia may not be modified.

Here is their flag.

https://www.flagcenter.com/usn-senior-executive-service-flag/

Here is their website.

https://www.opm.gov/policy-data-oversight/senior-executive-service/

Members of the SES serve in the key positions just below the top Presidential appointees. SES members are the major link between these appointees and the rest of the Federal workforce. They operate and oversee nearly every government activity in approximately 75 Federal agencies.